HetNet World 2015 – Event Report

This conference evolved from Informa’s earlier Small Cell and Wi-Fi series and has attempted to rebrand itself with both technologies combined under the HetNet title. Attendance was low but some delegates came from as far afield as Pakistan, Sri Lanka and Slovenia. With the large investments in LTE beginning to tail off in some countries, the debate centered around future investments: LTE-A, small cells, C-RAN and/or more Wi-Fi?

Where the big infrastructure investments are being made today

Analyst Stephane Teral of IHS reminded us that the annual macrocell equipment sales amount to some $45 Billion, but sees this peaking now that most initial LTE rollouts are in place and is expected to decline. By comparison DAS is around $2 Billion and Small Cells around $1 Billion. There are over 400 LTE networks live today and few large ones left who would make significantly large investments. China Mobile has already built out theirs with over 1 million basestations by the end of this year. The other two Chinese operators are also deploying 1 Million each, so this is where the action is.

He looks to Korea and Japan for signs of what might happen next, citing C-RAN as a popular option there, notably helped by extensive and low cost fibre availability. For those who do have access to dark fibre, SOLID explained how they've managed to squeeze 53 CPRI links onto a single fibre (the normal limit is about 7). Ultimately network operators will have to densify using small cells and many are at various stages of trialling, testing and perfecting deployment processes so they will be ready when the time comes.

Three UK want to keep traffic on their network

The keynote speaker was Erol Hepsaydir, Head of RAN and Device Strategy and Architecture at Three UK. Their network handles over 920 TBytes of data per day, a 14x increase over the last 5 years. 60% is streaming media and 26% web browsing. They engineer their network less for theoretical peak speed per individual and more for reliability and consistency. With 15MHz of 3G and 15MHz of LTE spectrum (at 1800MHz) they don’t have quite as much as some of their competitors. Take-up of LTE has been good, with almost a third of traffic now carried. Recently they’ve aggressively deployed a 5MHz sliver of 800MHz LTE to improve coverage and in-building penetration. Devices are encouraged to switch to higher bands whenever possible, saving this precious resource for those who need it most.

He considered a dozen 3GPP standards features which can be used to improve capacity and coverage, noting that half of them required device support (i.e. new smartphones) and so would take longer to return the benefits. Standard features such as ICIC, 4x2 MIMO, refarming 3G spectrum into LTE, Cell Range Extension and of course Small Cells can all reap the benefits immediately. His view is that many operators are actively trialling a few small cells, perfecting the deployment processes and financial models with stakeholders. The first few are unlikely to be quick or low cost, but lessons learnt can be re-invested to optimise the next batch and thereafter make further improvements.

For those in more challenging coverage areas, Three continue to deploy 3G femtocells and also have a standalone App (Three in Touch) for use with Wi-Fi. They’re looking at some public indoor femtocell deployments to address coverage issues and would prefer to keep customers “on-net” rather than offload to Wi-Fi.

No everyone has the option of using LTE

Guven Topcu of Turkcell points out that Turkey doesn’t yet have LTE (no licences awarded yet), so they’ve achieve a world first of 63Mbps over 3G by aggregating four 3G carriers. For such an unusual application, they had to design their own terminal to be able to use it.

Although 3G femtocells are a technical possibility, there is a national basestation tax which makes these unviable today. Their current strategy is primary for Outside-In coverage.

An innovative idea for a busy building which had an off-air DAS system in place was to install a small cell to drive that directly. What was unusual is that they created two sectors – one for the in-building system and one connected to the original off-air repeater antenna to serve the street area outside, converting it from a receiver (donor) antenna into a transmitter.

Amer Ejaz, General Manager (Carrier Services and Wholesale) for PCTL Pakistan, serving a population of over 200 million, simply can’t meet demand with a cellular network alone. Only 8 million of the nation’s 120 million subscribers have smartphones, growing quickly to 50 million by end 2016. Unlike some of the European operators views stated above, PCTL is driving an offload strategy and expect to offload 50% of their traffic by end 2016. They’ve chosen to deploy large numbers of Wi-Fi access points in the busiest locations, such as street markets. They see Wi-Fi as the only feasible option for these congested busy urban areas.

Delegates from Sri Lanka told me they do have an LTE network but only a relatively small proportion of customers can afford a smartphone and so most of their capacity is on 2G/3G.

Making the most of a sliver of spectrum

Martin Wren-Hilton, TalkTalk’s Director of Small Cell Technology, explained they would launch a service by deploying large numbers of residential broadband modems with built-in Wi-Fi and LTE femtocells – they have 3.8 million wireline broadband customers today and would ship upgrade/replacement units to their installed base over time. The have a narrow 3MHz band of LTE at 1800MHz. Wide area coverage will be provided by national roaming to Telefonica O2.

As a greenfield entrant, they’ll adopt the latest technology, which means VoLTE from the outset and their architecture supports seamless VoLTE handoff out to Telefonica (but not in). He believes the range and more consistent quality of the LTE will provide a better voice experience than on Wi-Fi, including outside to the street nearby. They are adopting an “Inside Out” approach unlike conventional operators.

When asked about LAA and its relevance for residential use, Martin notes that a superfast radio interface is worth nothing without backhaul to match. They are trialling fibre to the home which can achieve 940Mbps in York (priced the same as standard broadband at $30/month). LAA would allow them to make full use of that as a long term future development. I was surprised to hear that since 802.11ac is also included in their modem and can also achieve very high speeds.

Several speakers felt that LTE can outperform Wi-Fi given the same spectrum but I wonder what the penalty for LAA might be.

Wi-Fi Calling: Ready for commercial use or not?

I moderated a panel session on whether Wi-Fi Calling is ready for prime time yet (or not). There was a clear distinction between so-called “Over The Top Apps” which make voice calls over Wi-Fi and the relatively new Wi-Fi Calling or VoWiFi which is seamlessly integrated into the handset dialler and mobile network.

Pompeu Joao Costa, Senior Engineer at Portugese operator NOS, which has both fixed and mobile networks including a residential femtocell, plans to launch VoLTE first and then subsequently introduce VoWiFi. It would primarily be used to resolve poor indoor coverage problems especially in homes (e.g. basements).

Oracle and Broadsoft, who both supply the core network equipment required for VoWiFi (with and without Apps), were keen to point out that VoLTE wasn’t a pre-requisite for VoWiFi – there are architecture options to simplify that. While the service doesn’t match the full seamless mobility experience from a mobile network today, it can provide a good solution for those with poor indoor coverage who appreciate and understand the limitations.

Steve Dyatt, Head of Global Wi-Fi solutions at BT Wi-Fi, explained how they have enhanced their roaming hub to make some Wi-Fi networks look exactly like another mobile network. This removes a lot of the complexity previously needed to interwork and support Wi-Fi roaming.

Conclusion

There’s no single right answer or roadmap that would suit all operators in all countries. “Onload” operators have little interest in exploiting Wi-Fi and continue to focus on improving and maturing their LTE networks. Elsewhere “Offload” networks invest and encourage Wi-Fi use to relieve the strain.

Those operators with both fixed and mobile networks will be in the strongest position. TalkTalk explained how even a small amount of spectrum deployed in large numbers of residential homes can be used to capture a lot of traffic both inside and outside the home.

While we can see a lot of thought going in to maturing and evolving the cellular network, co-ordinating and orchestrating the HetNet will become more complex and more automated. As one speaker commented, nobody will be able to run an efficient network without SON and other automation tools five years from now.

Small cells certainly have their place in this next stage of network densification, with many delegates noting an upsurge of interest for medium/large buildings while the financial modelling and operational practices for more widespread deployment are being perfected.